A computer network is a collection of interconnected computing devices that can exchange data and share resources. In a packet-based network, such as an Ethernet network, the computing devices communicate data by dividing the data into variable-length blocks called packets, which are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form.
Certain devices, referred to as routers, maintain routing information representative of a topology of the network. The routers exchange routing information to maintain an accurate representation of available routes through the network. A “route” can generally be defined as a path between two locations on the network. Upon receiving an incoming data packet, a router examines information within the packet, often referred to as a “key,” to select an appropriate next hop to which to forward the packet in accordance with the routing information. Routers may include one or more packet processors, e.g., packet forwarding engines, and a switch fabric. Packet processors may receive and send data via interface cards. The switch fabric provides an interconnect mechanism for forwarding data between the packet forwarding engines for transmission over a network, e.g., the Internet. Routers use routing protocols to exchange routing information. Routers often maintain the routing information in the form of one or more routing tables or other data structures. Routers may generate and maintain forwarding information in accordance with the routing information.
Routers may use multiple redundant control plane routing components to redundantly maintain the routing information, thereby providing a more robust arrangement, in which at least one of the control plane routing components operates as a master routing component and the remaining control plane routing components operate as backup routing components. For proper operation, one and only one of the redundant control plane routing components should operate as the master routing component.